If you're not taking advantage of these "thin foods," you may be making the job of weight loss and long-term weight maintenance harder than they need to be.
"What we see in research studies is that food is more than the sum of its parts," says Cindy Moore, RD, director of nutrition therapy at The Cleveland Clinic in Ohio and a spokeswoman for the American Dietetic Association. "Foods that haven't been highly processed can have more than one effect in the body. Low-fat dairy foods are high in calcium and protein, but they also contain a range of other benefits that we are just beginning to understand in many cases."
And why not make that easier, she and other weight management experts say, by using what's easily available to help achieve your goals?
A small, but growing body of research has found an association between calcium intake and long-term weight management.
"It's really remarkable what we're seeing in research on calcium," says Moore.
Women with the highest intake of calcium from dairy foods, in relation to their total daily calorie intake, lost the most weight and body fat over two years, regardless of exercise, according to a study in the December 2000 Journal of the American College of Nutrition. Although the recommended calcium level for young women is 1,200-1,500 milligrams (mg) daily, the study found that the average woman's daily intake of calcium was under 800 mg per day.
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"Calcium appears to suppress a highly specific chemical in the vitamin D group," says Moore. "This chemical promotes the laying down of fat. It also slows the metabolism of fat. Calcium blocks this chemical, resulting in less stored fat and greater fat metabolism."
In fact, Moore says, animal studies have shown that sufficient calcium can even raise your body's core temperature. More fat is burned to keep your body warmer. But this finding has yet to be confirmed in humans.
"Ideally, three servings of low-fat dairy products would give you the recommended amount of calcium, which is enough to suppress the fat-producing chemical," says Moore. "It's always better to get your nutrition from foods, but calcium supplements have nearly as great an effect."
In addition, the weight lost comes largely from the midsection. Fat deposits in this are a risk factor for heart disease.
"We don't know for sure exactly how the calcium causes these changes, but it's consistent across the studies," says Greg Miller, PhD, director of nutrition and science affairs for the National Dairy Council. "People who ate more dairy seem to partition energy into lean body mass rather than into fat storage."
Here are the calcium levels recommended for adults by the USDA:
Age 9 to 18: 1,300 mg
Age 19 to 50: 1,000 mg
Age 51 and over: 1,200 mg
That all sounds good, but what if you're picking out a calcium supplement? There's calcium carbonate, calcium citrate, coral calcium. There are dozens to choose from.
"Calcium carbonate or citrate doesn't matter," says Moore. "What's more important is that the supplement also contains vitamin D. That combination is what you need to maximize calcium's effects."
An interesting side note to the larger calcium story is emerging in research on soy protein and soy isoflavones. An article in the American Journal of Clinical Nutrition in December 2002 found in soy many of the same properties that have been seen in calcium. More research in soy's potential weight-loss properties is ongoing, but it is too early to say whether early findings will hold up in larger trials.
Sure, your body needs water to metabolize stored fat, among other functions, so drink lots of it. But the amount of water in your food can also be important for weight management.
"Drinking water before or during meals has not been shown in studies to not do much in terms of reducing calorie intake," says Clare Hassler, MD, director of the Functional Foods for Health Program at the University of Illinois. "But when people eat foods that have high water content, they feel fuller longer and consume fewer calories. And this effect is independent of the food's fiber content."
Most fruits and vegetables are between 80% and 90% water. But there are some high-protein foods that also contain lots of water. Eggs and fish, for example, are nearly 70% water. And soup appears to give that fuller feeling far longer than some denser, more caloric foods.
"Most of Americans get only about 10 to 12 grams of fiber a day, and that is far too little" says Hassler. "Just about every health organization recommends getting between 30 to 35 grams for adults."
Hassler says that low levels of fiber can contribute to a wide range of chronic health problems and diseases, including certain cancers. And in terms of weight management, people who get too little fiber are missing out.
"Fiber provides a kind of bulk, which gives us the physiological feeling of fullness," she says. "It can replace calorie-dense, fatty foods from the diet."
So what is fiber exactly? It is an indigestible plant product. Since your body can't digest it, it has no calories. Fruits and vegetables are some of the best sources of fiber.
"Fiber-rich foods can be an important tool in weight management," says Moore.
John Casey is a freelance writer in New York City.
Published May 9, 2003.
Medically updated Dec. 7, 2004.